at the time of this thread, multi-core optimized OS and games has existed. 4 cores of course is better than 2 cores. In Vista, at any time u can find the number of threads is around 900 to 1000, although not all are active at the same time but it do helps by alleviating the kesesakan by handling 4 threads at one time. U can choose which task belongs to which core "CPU" in Vista task manager, have folding run at one core, HD movie run for another, the rest leave to windows.